A unique feature of the ellipsoidal bodies in a static magnetic field is uniformity of the field intensity \(\textbf {H}\)  (also called the magnetizing force, field strength, etc.) throughout their volume, as it was first shown by Poisson [1]} and discussed by Maxwell [2]}. The intensity \(\textbf {H}\)  is responsible for magnetization \(\textbf {I}(=\chi \textbf {H})\) . Depending on a demagnetizing field \(\textbf {H}_d(=4\pi \eta \textbf {I}\) ), in diamagnetics \(\textbf {H}(=\textbf {H}_0-\textbf {H}_d)\)  is greater than or equal to \(\textbf {H}_0\)  in magnitude, and its direction can differ from that of the applied field. \(\textbf {H}\)  is the field acting on “native" (belonging to the body) charges, whereas the induction \(\textbf {B}\)  is the field acting on a “foreign" (extraneous) chargesOn that reason the field measured by a prob charge, e.g., in \(\mu \) SR, is \(B\) , whereas in magnetic resonances the measured or controlling field is \(H\) .. Contrarily to \(\textbf {B}(=\textbf {H}+4\pi \textbf {I})\) , the average of microscopic fields caused by all native charges, \(\textbf {H}\)  does not include the field due to the charge in questionHere, the charge should be understood as the current caused by all types of microscopic movement, including the spinning one, of a given charge.. Respectively, in any medium \(\textbf {H}\)  differs from \(\textbf {B}\) . On the contrary, in a free space (vacuum) \(\textbf {I}=0\)  and, consequently, \(\textbf {\textbf {H}}=\textbf {\textbf {B}}\)Important that this is not just a mathematical coincidence, but a physical identity. This implies that in any system of physical units the dimensions of \(\textbf {B}\)  and \(\textbf {H}\)  must be the same..
